Lock or float

A rate lock freezes your interest rate for a set window — commonly 15, 30, 45, or 60 days — tied to how far out your closing is. Once you’re locked, if rates climb before you close, you’re protected: you keep your locked rate. Floating means leaving your rate unlocked and exposed to the market, betting it’ll improve before you have to lock in order to close.

That’s the whole decision. Pay nothing now and carry the risk, or fix your number and give up the upside. Everything else is detail on those two paths.

A lock is insurance, not a discount

It helps to see a lock for what it is: protection against one specific risk — rates rising between today and your closing. It does nothing for you if rates fall, because you’re fixed at your locked number unless you’ve arranged a float-down. And it isn’t a better rate than floating would have gotten you in the moment — it’s the same rate, frozen.

What you’re buying is certainty. If a quarter-point rise would push your payment past what you’re comfortable with, that certainty is worth a great deal. If you’ve got plenty of room in the budget, it’s worth less. The value of a lock is entirely a function of how much a higher rate would actually hurt you.

Float-downs, extensions, and what they cost

A lock isn’t a single fixed thing — there are a few moving parts, and each has a price:

• Float-down. Some locks include or offer a one-time float-down: if rates drop meaningfully before closing, you can capture the lower rate once. It usually costs something — a fee or slightly worse starting pricing — and has a minimum-drop trigger. It’s the “lock, but keep some upside” option.
• Lock extension. If your closing slips past your lock’s expiration, you extend it — and that costs money, often priced per day. A 60-day lock that needs another two weeks is not free.
• Longer locks are priced worse. A 60-day lock carries slightly worse pricing than a 30-day, because the lender is carrying the risk longer. You pay for the extra time, whether or not you end up needing it.

None of these are gotchas. They’re the price of certainty, and they’re worth knowing before you assume a lock is a free option.

How to actually decide

Three things drive it, and none of them is a guess about where rates are headed:

• How far out is closing. The longer the window, the more can happen, and the more a lock is worth. A closing 45 days out carries more rate risk than one 10 days out.
• How much room you have. If the payment only works at today’s rate, lock — don’t gamble money you actually need. If a higher rate would just be mildly annoying, you can afford to float.
• What you can stomach. Floating and watching rates tick up is stressful in a way that can sour an entire purchase. Certainty has a psychological value, not only a financial one.

Anyone who tells you they know where rates are going is guessing

Here’s what I won’t do: tell you to float because rates are “definitely” dropping, or to lock because they’re “about to spike.” Nobody knows — not me, not the loan officer at the call center, not the guy on the podcast. Rates move on inflation data, Fed decisions, and global events that nobody times reliably. Anyone selling certainty about direction is selling confidence they don’t have.

What I can do is give you the real cost of each path for your specific scenario, and help you make the bet with clear eyes — which is a very different thing from pretending it isn’t a bet.

Locking and buying down are different decisions

Don’t confuse locking your rate with buying it down. Locking fixes whatever rate you have against market movement. Buying it down — paying points — lowers the rate itself, locked or not. They’re separate choices that interact: you lock a rate, then decide whether paying to lower it pays off over the time you’ll hold the loan. Whether that trade is worth it is its own calculation, covered in should you pay points and on the discount points calculator.

Where this fits